Electrical switch device



June 1967 R. B. EDELSON 3,324,267

ELECTRICAL SWITCH DEVICE Original Filed Jan. 23, 1962 2 Sheets-Sheet 1 FIGI.

FIG.2.

ROBERT B. EDELSON INVENTORZ ATTYS.

June 6, 1967 R. B. EDELSON 3,324,267

ELECTRICAL SWITCH DEVICE Original Filed Jan. 23, 1962 2 Sheets-Sheet 2 FIGS.

INVENTOR'. ROBERT B. EDELSON 54 ATTYS,

United States Patent 3,324,267 ELECTRICAL SWITCH DEVICE Robert B. Edelson, Philadelphia, Pa, assignor to King- Seeley Thermos Co., Ann Arbor, Mich, a corporation of Michigan Continuation of application Ser. No. 168,178, Jan. 23, 1962. This application Oct. 4, 1965, Ser. No. 496,241 8 Claims. (53E. 2tl9153) This is a continuation of my application Ser. No. 168,178 filed Ian. 23, 1962, for Electrical Switch Device.

This invention relates to electrical switch devices, and more particularly to operating mechanisms in manually controlled switch devices of the rotary type.

In the production of electrical control switches, a basic switch design may have a wide variety of appilcations. Where surface mounting of such switches is acceptable, standardized units may be manufactured, calibrated, and tested in quantity, permitting prompt delivery at a relatively low cost because of the advantages of mass production. However, for aesthetic or other reasons, a large proportion of such switches need to be incorporated into the structure that they are intended to control, and standardization of the complete unit is therefore not possible. In order to adapt a rotary switch to built-in conditions, the part that most frequently requires special consideration is the control shaft. This may entail variations in shaft length, a special orientation of the knob and dial to permit uniformity of arrangement in spite of variations in the orientation of the switch, and/or other specific provisions. Even in connection with a particular product for a single industry, such as in the production of electric ranges, these requirements will vary from one manufacturer to another and from one model to another. As a result, final assembly and testing has not been possible heretofore until the shaft specifications have been made available and the desired shafts have been produced.

It is an object of this invention to provide a rotary switch device that may be manufactured in any desired quantities, and that may be stocked after calibration and testing, whereby complete units may be supplied promptly once the preferred shaft design is known.

It is a further object of the invention to provide a rotary switch adapted to replace one already in service, without needing to replace the shaft and its attached parts, such as knob and dial.

It is another object of the invention to provide a rotary switch, the mounting conditions of which may be changed by merely replacing the shaft with one designed to meet the changed conditions.

A further object of the invention is to provide a switch of the above type that may be manufactured inexpensively.

Briefly, the invention contemplates providing a self-contained switch device, having means for installing interchangeable shafts of simple construction. For purposes of test and calibration, a suitable shaft of any available style may be used, after which the test shaft is removed, to be replaced by one fulfilling the customers specific needs.

For illustrative purposes, the present invention is described as it is applied to an infinite switch of the general type described in the co-pending application of D. E. Clapp, Ser. No. 149,970, filed Nov. 3, 1961, although its use is not intended to be limited thereto. In the following discussion, reference will be made to the details of the switch mechanism only to the extent necessary for a complete understanding of the invention.

In the accompanying drawings:

FIGURE 1 is a perspective view of the exterior of a housing for a thermally actuated switch device;

FIGURE 2 is a plan View of the contents of the housing, with cover plate removed;

3,324,257 Patented June 6, 1967 FIGURE 3 is a sectional view taken along line 33 of FIGURE 2 showing the infinite switch construction with the cover in place and the knob attached;

FIGURE 4 is a sectional view similar to that of FIG- URE 3 taken along line 4--4 of FIGURE 2;

FIGURE 5 is an external view of the control shaft and associated parts taken parallel to the axis of the shaft;

FIGURE 6 is a similar external view of the control shaft taken at to FIGURE 5;

FIGURE 7 is an end view of the control shaft taken along line 77 of FIGURE 5;

FIGURE 8 is a plan view of the front of the housing with cover in place and the knob removed;

FIGURE 9 is a partial sectional view taken along line 99 of FIGURE 4;

FIGURE 10 is a detail view of the shaft at the rear of the casing; and

FIGURE 11 is an exploded perspective view showing the shaft, cam and knob assembly.

As shown in FIGURE 1, the switch device comprises a casing 11 formed of insulating material such as a rigid phenolic resin, and a cover plate 11 secured to the casing by suitable fastening means 12 and 13. The casing and cover plate form a housing for the component parts of the device, which includes manually adjustable means comprising a rotatable knob 14, including a dial 14a movable relative to indexing mark 11a on the cover and having suitable indicia positionable relative to the indexing mark to indicate when the switch is in Off position and various specific heat positions.

Within the housing are a pair of switch structures designated 15 and 16 (see FIGURE 2). Switch structure 15 is an On-Off switch having a movable blade 17. If desired, blade 17 may be bifurcated, as shown, to additionally control an auxiliary circuit, including a pilot light or the like. A cam follower 17a of inverted V-shape is formed in blade 17. Switch structure 16 is an adjustable thermostatic switch having an adjustable current carrying blade 18. As seen in FIGURE 3, blade 18 has one end secured to the casing, and its free end carries a contact 19. A strut 2t) is attached to the free end of blade 18 while it other end bears against a plate 21. Intermediate the two ends, it is formed to provide an inverted V-shaped cam folloW- er 20a.

The cam followers 17a and 26a are actuated by a circular rotatable cam 24, as seen in FIGURES 4, 9 and 11, constructed of molded insulating material such as Bakelite, having cam races 25 and 26 adapted to engage, respectively, cam followers 20a and 17a. Race 26 is shaped in such manner as to keep the contacts of switch 15 in engagement in all On positions, and to permit them to open in the Off position. Race 25 is so shaped as to move contact 19 into its opposing contact 27, which is thereby progressively displaced as the cam is rotated, so that progressively greater movement of contact 27 is required to open the switch 16. Contact 27 is supported by a bimetallic element 28 which is oriented in such manner as to separate the contact when heated. The heat is derived from a resistance heater 3% which is in intimate heat-transfer relationship with the bimetal 28 and is connected in circuit with the contacts 27, 19.

In operation, when cam 24 is moved to any 011 position, contacts 19 and 27 are engaged and current flows through resistance heater 30. After an interval of time heat from heater 30 causes bimetallic element 28 to flex sufficiently to open the contacts. This deenergizes heater 3% and the bimetallic element then cools until contacts 19, 27 again close. The cycle is continuously repeated, the ratio of On to Off time being determined by the extent to which contact 27 is displaced by contact 19.

In order to maintain the cam race contours in predetermined relationship with the cam followers, a reference race 31, is provided to engage supports 32 which extend from the rear wall 33 of the casing 10 and preferably are formed integrally therewith. Positive engagement is assured by spring means now to be described.

As shown in FIGURE 4, the cam is of stepped, generally conical form and of decreasing diameter toward the back of the structure, the active cam surfaces being the treads of the steps. The broad outward facing base of the cam structure 24 includes an annular, coaxial channel or recess 35 defining a centrally located circular hub boss 36. A sheet metal spring spider 37 seen best in FIGURE 11 fits over the outside of boss 36 with its resilient legs 37b arranged to engage the bottom of recess 35. The central portion 37a of the spider is an annular disc 41, and the legs 37b are so proportioned that there is clearance between disc 41 and the top of boss 36 initially when the spider is placed in position. Cover plate 11 includes a centrally located annular depression 42 and a tubular extension 43 arranged to be snugly engaged within bore 36a in the hub boss 36 of cam 24. A flat inner face of depression 42 is adapted to bear against disc 41 of spider 37. A gasket 44 is fitted over tubular extension 43, positioned between spider portion 37a and cover plate 11, the gasket being preferably of anti-frictional material such as nylon. When cover plate 11 is secured to casing 10, spider 37 is compressed and its resilient legs 37b force cam race 31 of cam 24 against supports 32, thereby positioning the races 25 and 26 in their operative positions against their cam followers.

The smaller diameter inner end of cam 24 terminates in a boss 45 having a central bore 46, provided with a tapered portion 47 at its inner end. A plurality of axially extending radial slots 48 are formed in the wall of bore 46, terminating in a shoulder 50. As seen in FIGURE 10 aligned with bore 46 is a circular aperture 51 in the base of the casing, which aperture also includes a plurality of slots 52.

FIGURES 5, 6 and 11 illustrate the control shaft 53 which supports cam 24 within the housing 10, 11 and knob 14 outside of the housing. Extending longitudinally parallel to the axis of shaft 53 is groove 54 along which extends a leaf spring member 56. Leaf spring 56 has opposing transverse arms 57 bent to embrace the shaft in a region narrowed by annular groove 55 whereby the leaf spring is properly positioned. One end of the leaf spring is formed outward and is provided with a radius 58 whereby when spring 56 is pressed inward sufficiently its end 60 will engage the bottom of groove 54. The outside diameter of shaft 53 provides a sliding fit in aperture 51, bore 46, and tubular extension 43 in cover plate 11.

To assemble the switch the end of the shaft 53 opposite spring 56 is passed through aperture 51 so oriented that portion 58 of the spring registers with one of slots 52. When the spring member reaches the cam, which is in place having been assembled as previously described, the shaft is rotated so that spring portion 58 enters one of slots 48 in cam hub 45. The tapered portions 48a of the selected slot urges spring 56 inward so that it is under stress when it reaches shoulder 50. The shoulder prevents further axial movement, but in this position the leading end of shaft 53 has passed through the cam and the tubular extension 43 of plate 11 leaving the end exposed for attachment of the knob 14. The shaft is rotatably supported in the housing by aperture 51 at one end and by tubular extension 43 at the other. As shaft 53 is rotated, the cam rotates with it because of the engage- 4 ment of leaf spring 56 with slot 48.

It will be seen from FIGURES and 6 that a second leaf spring 62 similarly secured by transverse arms 63 embraces the shaft in the reduced diameter region of annular groove 64. It will be apparent to those skilled that the arms 63 (as Well as arms 57 of spring 56) may be further held in place by swaging or such other attachment techniques which may prove necessary or desirable.

This spring has a V-shaped projection 65 which projects outside groove 54, but it is so shaped that it may be compressed into the groove by axial pressure and therefore it does not interfere with sliding the shaft into position. Spring 62 is provided for the removable attachment of knob 14, which includes a bore 66 of such diameter as to slip over the end of shaft 53. Within the bore is provided a flat chord bounding wall 66a arranged to engage spring 62. Opposed to the chord, there is a rib 66b provided to enter longitudinal groove 67, which is formed in shaft 53 parallel to groove 54 and diametrically opposed to it. Knob 14 drives the shaft through rib 66b, and the tension of spring 62 holds it securely in the axial direction during use, but permits its removal when desired. The outer face of cam 24 is inscribed with indicia corresponding to an Off position and various heat positions and a Window 69 is arranged through cover plate 11 (as seen in FIGURE 8) so that these indicia can be seen after the plate is assembled to the casing. A plurality of tapped holes may be provided in cover plate 11 for mounting purposes (for example, against the back of an electric range control panel). As seen in dotted lines in FIGURE 8, a spring member 72 is mounted within the casing arranged to engage depressions 73 in the outer diameter of cam 24 to act as a detent to determine the Off position and various heat positions.

In practice, switch devices as described are assembled in their housing; and any available shaft is slipped into place for testing and calibration. The latter operation is performed at a given heat position as viewed through window 69 and as determined by the detent corresponding to that heat. The test shaft is then removed and the switches are carried in stock awaiting an order. When the customer determines the manner in which the switch will be oriented in assembly, and supplies whatever other information is required for his specific requirement, suitable shafts can be made expeditiously by cutting off a portion of a length of bar stock in which the longitudinal grooves have been previously formed, and adding the necessary annular grooves and leaf spring. The shafts are then slipped into the switches, and are secured against subsequent axial movement by pressing a split ring 75 into annular groove 76, which is positioned to be adjacent the outside of cover plate 11 in depression 42. This completes the assembly except for the installation of suitable knobs after the switches are mounted.

Although only a single embodiment has been described, modifications will occur to those skilled in the art, and it is intended that the appended claims shall cover such modifications as do not depart from the scope and spirit of this invention.

I claim: 1 V

1. A switch device comprising a casing and a cover plate forming a housing, replaceable control shaft means rotatably mounted in said housing, one end of said control shaft means extending outwardly beyond said housing, a manually operable control knob removably mounted on said one end of said control shaft means, switch means mounted in said housing, cam means rotatably mounted in said housing and being operatively connected to said switch means, a control bore extending through said cam means, the other end of said control shaft means extending through and beyond said cam means opposite said manually operable control knob, an access opening in said housing permitting said control shaft means to be inserted into said control bore of said cam means from the side of the cam means opposite said manually operable control knob, a locating surface provided on said cam means to locate said cam means in said housing, support means in said housing for abuttingly engaging said locating surface on said cam means, spring means mounted between said housing and said cam means and biasing said cam means into engagement with said support means, at least one axially extending radial groove formed in said cam means and intersecting said control bore, stop means provided in said groove by a transversely extending shoulder means facing said other end of said control shaft means, a radially outwardly tapered approach surface provided in said groove and extending away from said stop means, a second spring means fixed to said control shaft means, .a portion of said second spring means being received in said groove to provide a driving engagement between said control shaft means and said cam means, and a portion of said second spring means abuttingly engaging said stop means to locate said shaft means in said control bore of said cam means.

2. The invention as defined in claim 1 and wherein said second spring means comprises a leaf spring attached to said control shaft me ans.

3. The invention as defined in claim .1 and having a plurality of circumferentially spaced axially extending radial grooves formed in said cam means.

4. The invention as defined in claim 2 and wherein said control shaft means includes a circumferential groove positioned to be adjacent the outer face of said cover plate when said leaf spring is seated in said groove, and a split ring is pressed into said groove to retain said control shaft means against axial movement.

5. The invention as defined in claim 2 wherein said control shaft means includes spring retaining groove means comprising a groove extending in an axial direction, a circumferential groove intersecting said axially extending groove, said leaf spring extending lengthwise within said axially extending groove and having a curved end arranged to project outside said groove, and including transverse opposed arms embracing the bottom of said circumferential groove arranged to hold said leaf spring in position.

6. The invention as defined in claim 1 and having means for ascertaining the angular position of said cam after the cover plate is secured to said casing.

7. The invention as defined in claim 6 wherein a window is provided in said cover plate, and indicia are marked on the outer face of said cam visible through said window, to represent selected cam positions.

8. In a self-contained electric switch unit comprising a casing (10) and a removable cover plate (11) forming a housing for the component parts of the switch unit which include one or more switch devices (15), (16) operable through cam follower means (17a), (20a) by a rotatable cam member (12) operably connected to a rotatable control shaft member (53) extending through the housing through opposite aligned support apertures (43), (51) in and extending through said cover plate (11) and an opposite side wall (33) of said casing and extending through an aperture (46) in said cam member aligned with said support apertures with one end of said control shaft member extending outwardly of said housing for manipulation to impart rotative movement to said cam member, the invention of means enabling installation and replacement of interchangeable control shafts of simple construction after assembly of said unit without removal of said cover plate or any of the other component parts within said housing and comprising:

support means (31), (32), (36), (37), (42), (43) separate from said control shaft member rotatably supporting and axially locating said cam member within housing,

connecting means (45-60) operably connecting said control shaft member to said cam member to cause rotative movement of said cam member in response to rotative movement of said control shaft member and permitting axial sliding movement of said control shaft member relative to said cam member to permit said control shaft member to be associated with and disassociated from said cam member by axial sliding movement without removal of said cover plate and without disturbing the position of said cam member within said housing, said connecting means comprising slot means (48) in one of said members extending axially parallel to said aperture in said cam member and said control shaft member and extending radially relative to said aperture and providing force transferring abutment surfaces, and projection means in the other of said members extending axially parallel to said aperture and said slot means and extending radially to provide abutment surfaces engageable with the abutment surfaces provided by said slot means through which rotative force is transferred from said control shaft member to said cam member,

access means (52) associated with one of said apertures and being cooperable with said connecting means to permit axial sliding movement of said control shaft member and said connecting means therethrough for removal and insertion of said control shaft member and said connecting means through the one of said apertures without reomval of said cover plate and without disturbing the position of said cam member within said housing, stop means (50), located on one side of said cam member and being effective between said control shaft member and said cam member to limit axial movement of said control shaft member in one direction, and releasable holding means associated with said control shaft member on the other side of said cam member outside of said housing and being effective to limit axial movement of said control shaft member in the opposite direction and holding the control shaft member in operative association with said cam member until released to permit axial sliding movement of said control shaft member in the opposite direction.

References Cited UNITED STATES PATENTS 1,141,032 5/1915 Badeau 200-167 X 2,395,572 2/ 1946 Meuer et a1.

2,53' 1,246 11/ 1950 Batcheller 74-527 2,697,156 12/1954 Hortman et a1. 2001.-53.11 2,774,852 12/1956 Boardman 200-172 2,813,172 11/1957 WOjcik 200122 ROBERT K. SCHAEFER, Primary Examiner.

D. SMITH, JR., Assistant Examiner. 

1. A SWITCH DEVICE COMPRISING A CASING AND A COVER PLATE FORMING A HOUSING, REPLACEABLE CONTROL SHAFT MEANS ROTATABLY MOUNTED IN SAID HOUSING, ONE END OF SAID CONTROL SHAFT MEANS EXTENDING OUTWARDLY BEYOND SAID HOUSING, A MANUALLY OPERABLE CONTROL KNOB REMOVABLY MOUNTED ON SAID ONE END OF SAID CONTROL SHAFT MEANS, SWITCH MEANS MOUNTED IN SAID HOUSING, CAM MEANS ROTATABLY MOUNTED IN SAID HOUSING AND BEING OPERATIVELY CONNECTED TO SAID SWITCH MEANS, A CONTROL BORE EXTENDING THROUGH SAID CAM MEANS, THE OTHER END OF SAID CONTROL SHAFT MEANS EXTENDING THROUGH AND BEYOND SAID CAM MEANS OPPOSITE SAID MANUALLY OPERABLE CONTROL KNOB, AN ACCESS OPENING IN SAID HOUSING PERMITTING SAID CONTROL SHAFT MEANS TO BE INSERTED INTO SAID CONTROL BORE OF SAID CAM MEANS FROM THE SIDE OF THE CAM MEANS OPPOSITE SAID MANUALLY OPERABLE CONTROL KNOB, A LOCATING SURFACE PROVIDED ON SAID CAM MEANS TO LOCATE SAID CAM MEANS IN SAID HOUSING, SUPPORT MEANS IN SAID HOUSING FOR ABUTTINGLY ENGAGING SAID LOCATING SURFACE ON SAID CAM MEANS, SPRING MEANS MOUNTED BETWEEN SAID HOUSING AND SAID CAM MEANS AND BIASING SAID CAM MEANS INTO ENGAGEMENT WITH SAID SUPPORT MEANS, AT LEAST ONE AXIALLY EXTENDING RADIAL GROOVE FORMED IN SAID CAM MEANS AND INTERSECTING SAID CONTROL BORE, STOP MEANS PROVIDED IN SAID GROOVE BY A TRANSVERSELY EXTENDING SHOULDER MEANS FACING SAID OTHER END OF SAID CONTROL SHAFT MEANS, A RADIALLY OUTWARDLY TAPERED APPROACH SURFACE PROVIDED IN SAID GROOVE AND EXTENDING AWAY FROM SAID STOP MEANS, A SECOND SPRING MEANS FIXED TO SAID CONTROL SHAFT MEANS, A PORTION OF SAID SECOND SPRING MEANS BEING RECEIVED IN SAID GROOVE TO PROVIDE A DRIVING ENGAGEMENT BETWEEN SAID CONTROL SHAFT MEANS AND SAID CAM MEANS, AND A PORTION OF SAID SECOND SPRING MEANS ABUTTINGLY ENGAGING SAID STOP MEANS TO LOCATE SAID SHAFT MEANS IN SAID CONTROL BORE OF SAID CAM MEANS. 